The human eye functions to provide vision by transmitting and refracting light through a clear outer portion called the cornea, and further focusing the image by way of a lens onto the retina at the back of the eye. The quality of the focused image depends on many factors including the size, shape and length of the eye, and the shape and transparency of the cornea and lens.
When trauma, age, disease or other malady cause an individual's natural crystalline lens to become less transparent, vision deteriorates because of the diminished light which can be transmitted to the retina. This deficiency in the lens of the eye is often referred to as a cataract. The treatment for this condition is surgical removal of the natural crystalline lens and implantation of an intraocular lens (IOL).
While early IOLs were made from hard plastic, such as polymethylmethacrylate (PMMA), soft, foldable IOLs made from silicone, soft acrylics and hydrogels have become increasingly popular because of the ability to fold or roll these soft lenses and insert them through a smaller incision. Several methods of rolling or folding the lenses are used. One popular method is an injector cartridge that folds the lenses and provides a relatively small diameter lumen through which the lens may be pushed into the eye, usually by a plunger. One commonly used injector cartridge design is illustrated in U.S. Pat. No. 4,681,102 (Bartell), and includes a split, longitudinally hinged cartridge. Other designs are illustrated in U.S. Pat. Nos. 5,494,484 and 5,499,987 (Feingold) and U.S. Pat. Nos. 5,616,148 and 5,620,450 (Eagles, et al.), the entire contents of which are incorporated herein by reference for all purposes. Still other cartridges are described in U.S. Pat. No. 5,275,604 (Rheinish, et al.), U.S. Pat. No. 5,653,715 (Reich, et al.) and U.S. Pat. No. 5,947,876 (Van Noy, et al.), the entire contents of which are incorporated herein by reference for all purposes.
The cartridge is typically preloaded with an IOL and then used as part of a delivery system to deliver the IOL to an eye of a mammal (e.g., a human). The delivery system will typically include a hand-piece that includes a plunger within a housing. The delivery cartridge is attached to the hand-piece (e.g., to the housing of the hand-piece) and then the tip of the cartridge can be inserted into an eye of a mammal. The plunger can then advance the IOL along the lumen of the cartridge and into the eye. After IOL delivery, the cartridge is typically removed from the hand-piece so that the hand-piece can be reused with a different cartridge. This system, while generally desirable, has some drawbacks.
As one exemplary drawback, the plunger of the hand-piece or the entire hand-piece must typically be sterilized (e.g., by autoclaving) after delivery of an IOL. Such sterilization is typically required because the tip of the plunger often enters the eye during insertion of the IOL and it can retain biological matter after removal from the eye. The sterilization process can require significant amounts of time and can limit the number of IOL deliveries that can be accomplished in a given time span.
As another exemplary drawback, the plunger of the hand-piece is typically sized to accommodate the size of a lumen of a particular cartridge. If it becomes desirable to use a new cartridge having a different size lumen, an entirely new plunger or entirely new hand-piece must typically be employed to accommodate that cartridge.
As yet another exemplary drawback, recent trends in IOL delivery systems have made the use of soft tip plungers quite desirable, however, the reusable plungers associated with these types of delivery system are often formed of metal or some other autoclavable material and providing such materials with a soft tip can be problematic.
It would be quite desirable to provide a plunger for an intraocular lens delivery system where that plunger overcomes one or more of the aforementioned drawbacks and/or additional drawbacks associated with conventional IOL delivery systems.